Bab McLagan started seeing the man who would become her husband back in the eighth grade. Now, after 36 years of marriage, she's waiting for a judge to sign divorce papers.

"I was in it for the long haul," said McLagan, 57, of Minneapolis. "Then I found out he was seeing someone else, and it was time to go our separate ways."

The breakup of a decades-old union is all too common. A quarter of all divorces in 2007 involved couples who had been wed 20 years or more, according to the U.S. Census Bureau. Most of those opting not to wait "till death do us part" are baby boomers, the most divorce-prone generation in history.

Experts say the growing number of "gray divorces" often end more with a whimper than a bang.

"They tend to be less acrimonious," said Ron Ousky, an Edina-based attorney and mediator, "a little more of a sense of, 'Let's try to keep what we have. We want to be able to go to graduations and weddings and bar mitzvahs or whatever for our grandkids.'"

Ousky said most of the cases he sees are "what feels like a 'fadeaway divorce' as opposed to divorce by crisis."

Matt Weiser, 50, of New Hope called his 23-year marriage's dissolution "largely just kind of a disaffectation."

LaDonna Redmond, 47, of Minneapolis said she and her husband just grew apart.

"We didn't love each other, not the way a married couple should," she said. "It turned into a brother-sister relationship. The intimacy was gone."

Also gone are most of the religious and societal taboos that surrounded divorce until the rise of baby boomers -- people born from 1946 to 1964 -- along with the financial dependence that women of previous generations faced. All of these developments make it easier for longtime couples to split when root causes such as midlife crisis, empty-nest syndrome or alcohol abuse hit.

While only 23.4 percent of people over 70 have been divorced, that number jumps to 35.7 percent for people in their 50s. While Minnesota has a lower divorce rate than the nation among those under 45, the state is on par with the rest of the nation for boomers, said Steven Ruggles, director of the Minnesota Population Center.

Life changes stir the pot

Often, a couple wake up one day with the kids gone and wonder what they still have in common. But Ousky also sees splits in multichildren households when the youngest kid is still in high school.

"You see it when the last one is just about out of the nest, but not quite," Ousky said. "Maybe it's a cliché, but [the couple have] been absorbed with two or three kids and realize, 'We now have to have a life together.' The reality is you spend less time on the relationship with each other because it's so easy to be consumed by jobs and parenting. You click into business mode and say, 'We'll revisit the relationship later.'"

That's what McLagan said happened in her marriage: "We got disconnected, totally into what the kids were doing." Her husband, she said, didn't know what his role was anymore.

And then there's the proverbial midlife crisis. Weiser said his wife's "red convertible was the cabin on the lake."

But even while Ousky jokes that he has considered placing brochures for prospective divorce clients at a Harley-Davidson dealership, he and other attorneys, including Minneapolis divorce attorney Jane Binder, say "life changes" take many forms.

"I've seen cases where one of the spouses becomes an exercise fanatic, or they decide they want to spend money differently," Binder said. "Usually, the one going through the big change is the one who wants to start afresh. And the other one is often caught like a deer in headlights and goes, 'What just happened here? I was on a path, and you just left that path.'"

Binder also said alcohol has affected her cases with clients in their 50s and 60s. "One party can't stop, and the other party can't live like that anymore," she said.

Empowered women file more

Women, who in previous generations might have stayed in a marriage because of financial, religious or social repercussions, are increasingly the ones filing for divorce.

In fact, a 2004 AARP study found that 66 percent of the filings were made by wives. But Binder said women might be taking action only because their husbands are not.

"They're not necessarily the ones who initiated the decision," she said. "They're just frustrated by the situation. Even if they weren't the one saying, 'I don't love you anymore' or having the affair, if it's too stagnant, they're more comfortable getting the lawyer or getting the papers started."

Part of that comfort level is because, as Ousky notes, "there's less of a stigma than there was when I started practice 20 years ago."

But a bigger factor might be that today's midlife women are "more often in a better financial situation than our mothers and grandmothers were," Binder said.

Redmond, a longtime community organizer, is an example. "I wasn't worried if I could take care of myself," she said. "I was more worried about [family logistics]."

The same was true for Deb Fox, 52, of Plymouth: "I knew I could work. I've always worked."

While women continue to work, those of a certain age who have gone through a divorce "are much less eager to get remarried than men are," said Stephanie Coontz, author of "Marriage: A History." "Very frequently, the women are in an 'I'm ready to move on' mode."

As a result, people over 50 are the fastest-growing group of cohabitants, Coontz said.

"They frequently partner up, but they don't want to complicate their lives," she said. "Your chance of being able to remarry at an older age is better than ever, but a lot of them just don't want to make that commitment."